1. Field of the Invention
One or more embodiments of the present invention relate to a polymer battery pack in which a top case is coupled to a lithium polymer battery cell molded by a mounting frame.
2. Description of the Related Art
In general, secondary batteries may be charged or discharged, unlike a primary battery, which may not be charged. Secondary batteries are used as energy sources of small-sized devices, such as a cellular phone, a laptop computer, and a camcorder, and medium-large sized devices such as an electric car, a hybrid electric car, an electric bicycle, and a uninterruptible power supply (UPS).
A lithium secondary batteries is an example of a secondary battery. The lithium secondary battery may be classified into a can-type secondary battery, which has a cylindrical or square shape according to the shape of a case accommodating an electrode assembly, and a pouch-type secondary battery having flexibility.
Secondary batteries may be classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte. In general, a battery using a liquid electrolyte is referred to as a lithium ion battery, and a battery using a polymer electrolyte is referred to as a polymer battery. Lithium-ion polymer batteries, polymer lithium ion, or more commonly lithium polymer batteries (abbreviated Li-poly, Li-Pol, LiPo, LIP, PLI or LiP) are rechargeable batteries (secondary cell batteries).
Many cells sold today as polymer batteries are pouch cells. Unlike lithium-ion cylindrical cells, which have a rigid metal case, pouch cells have a flexible, foil-type (polymer laminate) case. In cylindrical cells, the rigid case presses the electrodes and the separator onto each other; whereas in polymer cells this external pressure is not required because the electrode sheets and the separator sheets are laminated onto each other.
Since individual pouch cells have no strong metal casing, by themselves they are over 20% lighter than equivalent cylindrical cells. However, all Li-Ion cells expand at high levels of SOC (State of Charge); if uncontained, this may result in delamination, and reduction of reliability and cycle life; the case of cylindrical cells provides that containment, while pouch cells, by themselves, are not contained. Therefore, to achieve the rated performance, a battery composed of pouch cells must include an overall, strong, external casing to retain its shape.
Conventionally, a battery cell accommodating an electrode assembly is coupled to a protection circuit module (PCM). A top case is installed on the battery cell coupled to the PCM. In addition, the battery cell is inserted into a film-type outer case by using a double-sided tape, and a label is attached on an outer surface of the outer case. A battery pack is manufactured through the above-described processes.
However, a conventional battery pack requires a large number of processes and causes a severe poor distribution due to a worker. Insert injection process performed during a manufacturing process of a battery pack may affect the PCM and a positive temperature coefficient (PTC) element.